[PATCH 4/4] drm/amd/display: Restore deleted patch to resolve reset deadlock.

[Andrey Grodzovsky]

Patch '5edb0c9b Fix deadlock with display during hanged ring recovery'
was accidentaly removed during one of DALs code merges.

Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky at amd.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 0648794..27e0383 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -5138,14 +5138,21 @@ static void amdgpu_dm_commit_planes(struct drm_atomic_state *state,
 		 */
 		abo = gem_to_amdgpu_bo(fb->obj[0]);
 		r = amdgpu_bo_reserve(abo, true);
-		if (unlikely(r != 0)) {
+		if (unlikely(r != 0))
 			DRM_ERROR("failed to reserve buffer before flip\n");
-			WARN_ON(1);
-		}
 
-		/* Wait for all fences on this FB */
-		WARN_ON(reservation_object_wait_timeout_rcu(abo->tbo.resv, true, false,
-									    MAX_SCHEDULE_TIMEOUT) < 0);
+		/*
+		 * Wait for all fences on this FB. Do limited wait to avoid
+		 * deadlock during GPU reset when this fence will not signal
+		 * but we hold reservation lock for the BO.
+		 */
+		r = reservation_object_wait_timeout_rcu(abo->tbo.resv,
+							true, false,
+							msecs_to_jiffies(5000));
+		if (unlikely(r == 0))
+			DRM_ERROR("Waiting for fences timed out.");
+
+
 
 		amdgpu_bo_get_tiling_flags(abo, &tiling_flags);
 
-- 
2.7.4